Grain carts are typically used to transfer grain or other crop material from a combine harvester to a grain truck or bin. The grain cart typically comprises a storage hopper for crop material, an auger assembly for emptying crop material from the storage hopper and a set of ground wells so that the grain cart can be towed. While smaller grain carts may have a single pair of wheels, larger grain carts now commonly have a tandem set of wells (two wheels on each side of the grain cart). A tractor is commonly used to tow the grain cart with the auger assembly of the grain cart being driven off of the power take off (PTO) of the tractor (although hydraulics, etc. could also be used to power the auger assembly).
In use, the grain cart is towed by the tractor to a combine harvester where the crop material is unloaded from the combine harvester into the grain cart. With the crop material loaded into the storage hopper of the grain cart, the tractor can tow the grain cart to a truck, trailer, storage bin, etc. and use the auger system to unload the crop material from the grain cart.
Grain carts are getting larger and larger and some are now quite large. The larger grain carts now use tandem wheels on each side of these grain carts so that these larger grain carts are supported by four wheels in total. However, these tandem wheels can make it hard to turn the grain cart if the wheels are fixed in position. Instead, it is desirable to have a wheel assembly that allows the wheels to pivot when the grain cart is turned in order to allow the wheels of the grain cart to follow a curved path while the components used in the wheel assembly are relatively simply and still allow the wheels to be fixed in place to make it easier or even possible to reverse the grain cart.